<Snipped quote by Double>
Kai plays with tactics not just brute force making him closer to smart guy, he could also act as lancer as a contrast with Naoki since they are both former player in teams and their specialties are opposites. I think Jun fits more with Big Guy due to his aggressive personality.
Well, Riku doesn't really fit Big Guy either. I mentioned one being able to make an argument for it, but that argument would be based entirely on the fact that he looks like a punk, therefore he must BE a punk. Riku has demonstrated by now that he leans far more toward being analytical, only skewing toward brute force for a brief moment while using God Hand Mode.
It's possible that nobody fits the Big Guy archetype, in which case the team as a whole no longer fits the Five-Man Band trope.
Instead, it looks a little more like this:
The Hero: Naoki
The Lancer/Smart Guy: Riku
The Lancer/Smart Guy: Kai
The Lancer/Smart Guy: Jun
The Heart?: Blade
Seems to be that Riku, Kai, and Jun are all varying degrees of Lancer and Smart Guy. Heck I wouldn't be surprised if Blade also is some degree of Lancer/Smart Guy as well. xD